Field of the Invention
The present invention pertains to the art of dishwashers and, more specifically, to a dishwasher including a sump which can be selectively employed with either a removable filtration system or a chopper pump system.
Description of the Related Art
Currently, there are two main wash systems utilized with dishwashers, i.e., chopper systems and filtration systems. In general, in connection with a chopper system, all soils in the washing fluid are directed to a chopping mechanism where the soils are made small enough to pass through the dishwasher's fluid pump, which distributes soil containing fluid to the spray arms of the dishwasher. At least some amount of this soil containing water is diverted to an accumulator/filter where soils are collected and separated from the water. A water nozzle from the spray arm sprays down onto a screen of the accumulator to keep the screen clean over the life of the product. Although chopper systems perform the function of reducing soil size, they also negatively impact the flow of fluid and load on the motor. This leads to a larger pump motor than would be required if no chopping function was performed. Such a system is also louder than simple filtration units because of the larger motor and the sound of the chopper blade turning in the water. Advantageously, chopper systems are self-cleaning, remaining maintenance free. One example of a chopper system can be seen in U.S. Pat. No. 7,404,864, which is incorporated herein by reference.
In a filtration system, soil that might restrict flow through the spray arm nozzles is captured upstream of a recirculation pump by filters in order to prevent the soil from re-depositing on dishware being washed. The filters are typically set up with multiple filters, including at least one fine filter that allows only small, non-nozzle blocking particles through to the fluid pump. One example of such a system can be seen in U.S. Patent Application Publication No. 2010/0037923, which is incorporated herein by reference. A brief description of the '923 dishwasher will now be discussed with reference to FIGS. 1-3.
In general, a dishwasher 2 includes a tub 5 having bottom, side and rear walls 8-11, as well as a top wall (not shown). Tub 5 defines a washing chamber 14, which is selectively sealed by a door 20 including a detergent tray 23. Disposed within tub 5 is a filtration system 30 including a central main strainer or filter screen 36 and a secondary strainer 39. A heating element 44 is positioned above bottom wall 8. A circulation pump (not shown) directs washing fluid from a sump unit 50 (seen in FIG. 2) to a fluid distribution manifold indicated at 53. In a manner known in the art, fluid distribution manifold 53 supplies washing fluid to at least a lower wash arm 55 and a conduit 57 leading to an upper spray arm (not shown). Fluid distribution manifold 53 is also in fluid communication with spray manifold assembly 59, including a plurality of spray discs 62. As depicted in FIGS. 2 and 3, sump unit 50 generally includes a sump enclosure 68 and a recessed main intake 73 having an outlet or recirculation intake port 80 leading to a circulation pump (not shown). Filter screen 36 constitutes a first-pass screen filter having a shape that aids in channeling washing fluid across the screen to secondary strainer 39. In general, washing fluid flows through a screen portion 75 of strainer 39 before entering main intake 73 and exiting outlet 80. Filter screen 36 is substantially circular and is supported along its outer circumferential edge 90 by filter support surface 83 and seals against filter support surface 83. Filter screen 36 includes a main body portion 100 having an aperture 105 there through and arm portions 108 and 109 which define a central opening 112 in the form of a slot there between. When assembled, central opening 112 fits around fluid distribution manifold 53 and aperture 105 extends over main intake 73. In this example, an additional filter (not shown) located adjacent exiting outlet 80 works alongside filter 39 to capture soil particles upstream of a fluid recirculation pump (not shown) in main intake area 73, and allows these soil particles to pass through a drain pump intake (not shown) when a drain pump is actuated.
With each type of washing system, there are positive and negative aspects. For instance, as indicated above in discussing the chopper system, a larger motor is generally required in order to drive both the pump and the chopper. With a filtration system, it is common for one or more of the filters to require periodic removal for cleaning by a consumer. In any case, both types of systems are desirable, simply for different reasons. To this end, both systems are commonly found on the market. Given the different requirements for each system, the tub, sump, pump mountings and other structural details are unique to the particular type of system. With this in mind, it would be advantageous to provide an overall dishwasher tub and sump arrangement which could be readily adapted for use with either filtration or chopper-type systems.